FrontEngineDragsters.Org Forum
Drag Racing Discussions => Front Engine Dragsters => Topic started by: DNCMOTORS on January 08, 2022, 11:36:39 AM
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I'm installing the engine for the first time in a new 200"frame. The motor is hanging and the rear of the engine is snugged up to the rear motor plate. I'm fabricating the front motor supports to rest on the frame. My question is should I have zero flex on the frame from the engine weight, or do I want some pre flex? The motor is hanging level in the car as it sits on the tires. Is this where I need to get my measurements for the front supports of the motor?
Thanks
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I did not preload my frame. Set engine to motor plate and made sure there was no distortion on the motor plate. Think balanced here. Measure for front mounts and tack together. Before final finish on front mounts set trans in place with complete driveline in place to make sure of alignment.
Hope this helps
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I never ran a rail, but my gut feeling is most of the chassis flex will be ahead of the front motor plate. Not much will be at the engine bay.
Having said that, it is still best to mount the front plate on saddles with clamps. "Not much" bend is still not zero, and twisting of the chassis due to the engine torque will put some stress in the block if the front mounts are not "saddled up".
Some builders use a bolted engine mount in double shear taps on the left side where torque tends to pull the plate up and a saddle on the right side where torque tends to push the saddle mount down on the frame rail.
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When I build a car the weight of the block is supported by the alignment bar and the bar is supported by the jig so naturally this leaves no preload on the chassis. As mentioned, if you're not using an alignment bar you'll probably come out way ahead to get all your driveline parts in place and make sure the coupler slides free through the whole process.
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on the feds sbc with long glide with a alignment bar set the motor then added saddle mounts on the top rail that had a tab welded to it and a grade 8 5/16" thru bolt then added a trans mount with insulator never broke a stock case even when doing a wheel stand high enough drag the rear of the frame (no wheelie bars) flattened both front rims.
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You mentioned a trans mount and I had wondered about the need for one. I'll be well under 300HP and wondered if just the front mounts and mid plate are all that are needed with a SBC and a stock length (28-ish inch) Powerglide, or if installing a mount at the tailshaft was common or necessary. I'll be using a short (not a collapsible?) coupler.
Lynn
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I use a mount, alot of people don't, I even use one on my altered with a shortie because of the driveshaft. at first a mount wasn't used and the bellhousing cracked we are talking about stock cases and I don't like transmissions hanging from the bellhousing
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I have a normal tail glide and use the mount on the tail shaft but it is mounted straight to the chassis no isolator
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tcoupekyle.....I guess the transmission and engine were installed and direct coupled to the pinion and then the mount was built to "meet" the mount boss on the tailshaft housing? Since the engine and transmission are solid monnted to the chassis through the midplate and front engine mounts, that would make sense to me.
I'm not disagreeing with anyone, believe me, I'm here to learn, but must say I'm surprised that tailshaft mounts are used in a close-coupled FED. I would have expected the coupler would be tasked with keeping alignment and minimizing the potential of distortion along with transferring torque.
Lynn
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I USED U-JOINT AND A SLIP YOKE , IT WAS JUST TO MAKE SURE THAT EVERYTHING WAS FREE
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This isn't related to this topic, so please forgive me, but did I click on something by mistake that keeps the list of "unread posts since last visit" from showing that can be clicked on to see if I missed anything without looking through the whole forum? It used to be just under the Forum name in the upper left corner of the page. Sorry for being off topic!
Lynn
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Not sure Lynn. The board has been quiet the last few days...
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I'm not sure on that either
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Still showing on my screen just under your user name. how's your build progressing Lynn 8)
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I just got the "unread posts" thingie back by clicking the arrow at the upper right hand corner of the home page. I guess I clicked it by accident, or....maybe my wife is reading the forum on my computer and did it? LOL
BTW....I'm going to try to resize and post a photo or two of my current progress on my "FED Build" thread.
Thanks
Lynn